There is a wide variety of closures disclosed in the prior art covering many different concepts. However, the conventional prior art closure is designed to be assembled to a container after the container is filled. To provide for a closure that can be assembled to the container before it is filled and yet still allow for filling, requirs that the closure or container include means to communicate with the package interior and a means for sealing the closure or container after the filling operation is completed.
Also, in production, the conventional closure involves a two-step filling operation requiring one step for filling and another for assembling the closure to the container opening after filling. For most filling applications this two-step filling and closing operation is satisfactory although not always very efficient, and it is vulnerable to the accidental introduction of extraneous matter into the container between the filling station and the closing station. The more desirable type of closure would somehow enable one to combine the filling and closing operations into a single operation.
One solution to this problem is to provide a closure having a filling inlet and a sealing plug, integrally connected to the closure which can be placed into the filling inlet immediately after filling. This approach is used in U.S. Pat. No. 2,952,278 issued on Sept. 13, 1960 to W. Waldherr which discloses a spray head and filling plug. The spray head, in the embodiment shown in FIGS. 1-6, is designed to be mounted on a container and includes a plug which is integrally molded with the spray head. The plug is initially driven part way into the bore of the spray head, blocking off the spray discharge passageway. The plug has a lateral hole that communicates with an axial inlet passageway that is located just above the container inlet. The container can be filled via this lateral hole and when the filling is completed and while the spray head is vertically supported by the valve cup wall, the plug can be driven full depth into the spray head, until the lateral hole in the plug is aligned with a spray discharge passageway. Another embodiment of the spray head, shown in FIGS. 7 and 8, provides for a series of integrally molded fins that project inwardly from the edges of a filling inlet communicating with the container inlet and which are joined to a centrally-located plug. The container to which the spray head is attached is filled via the gaps between the several fins and the plug and the inlet. After the filling operation is completed and, again, while the spray head is fully supported by the valve cup, the plug is driven into the valve stem upper end to seal it.
Each of the described Waldherr embodiments rely on structural means fully supporting the part bearing the plug seal at the time of closure. There is no teaching as to how such a filling concept could be accomplished using a package or equipment with which structural support is not present, e.g. where the integral plug is part of a molded piston-type closure.
According it is an object of the present invention to provide a closure means having a filling aperture that is closed and sealed by a plug in which the closure has no structural means to support it while the plug is being inserted into the aperture during sealing.
It is also an object of this invention to provide an economical closure means capable of allowing a piston actuated container to be filled and sealed in one operation.
Another object of the invention is to provide a one-piece piston-type closure having an integrally molded, detachable element for sealing the filling inlet in the closure.
Yet another object of the invention is to provide a container having a piston-type closure that is capable of withstanding repeated impact loads for the purpose of forcing a semi-liquid, viscous material through a plurality of dispensing outlets in the container.
Still another object of the invention is to provide a closure device that includes a means for signaling that the material in the container has been exhausted.